Suitability
LST scheduling is most useful in systems comprising mainly aperiodic tasks, because no prior assumptions are made on the events' rate of occurrence. The main weakness of LST is that it does not look ahead, and works only on the current system state. Thus, during a brief overload of system resources, LST can be sub-optimal. It will also be suboptimal when used with uninterruptible processes. However, like earliest deadline first, and unlike rate monotonic scheduling, this algorithm can be used for processor utilization up to 100%.
Read more about this topic: Least Slack Time Scheduling